Many procedures are known for the biotechnological production of 2′-FL such as by fermentation with transformed E. coli. Some of them have been investigated only with qualitative analytical methods without mentioning the yield of 2′-FL or how to isolate it from the fermentation broth (WO 2010/070104, WO 2012/007481, Lee et al. Microb. Cell Fact. 11:48 (2012)). Preparative methods have been performed in lab scale and not exceeded a final titre of 25 g/l of 2′-FL (Drouillard et al. Angew. Chem. Int. Ed. 45, 1778 (2006); M. Randriantsoa: Synthèse microbiologique des antigènes glucidiques des groupes sanguins, Thèse de Doctorat soutenue le 30 Sep. 2008 à l'Université Joseph Fourier, Grenoble, France; WO 2012/097950, WO 2012/112777; Baumgärtner et al. Microb. Cell Fact. 12:40 (2013)). According to these publications, 2′-FL has been isolated from the aqueous culture medium or supernatant, in which the E. coli was fermented, by:                separating the supernatant containing the product by centrifugation,        adsorption of 2′-FL on a bed of activated charcoal that was washed with water to eliminate water-soluble contaminants like salts, amino acids and protein fragments,        eluting 2′-FL with alcohol or aqueous alcohol, and then        separating 2′-FL from other carbohydrates like lactose and fucose by gel permeation chromatography or flash chromatography on charcoal-celite bed.        
The main drawback of this isolation method has been the need for chromatographic separation in order either to get pure 2′-FL or to obtain at least a mixture that is enriched in 2′-FL but still contains undesired derivatives. Although repeated chromatographic separations can result in the improvement of the purity, their high cost and relatively long times to handle the feed solution and the column packing, to carry out the separation and optionally to regenerate the packing, especially in large or industrial scale, can be disadvantageous and bothersome.
Crystallization or recrystallization is one of the simplest arid cheapest methods to isolate a product from a reaction mixture, separate it from contaminations and obtain pure substance. Isolation or purification that uses crystallization makes the whole technological process more robust and cost-effective and thus advantageous. In this regard, WO 2011/150939 discloses obtaining anhydrous 2′-FL polymorphs I and II, and WO 2014/086373 discloses crystallizing 2′-FL, using methanol, from a freeze dried powder, derived from an aqueous fermentation broth. Moreover, WO 2014/009921 discloses, using acetic acid, to crystallize 2′-FL sesquihydrate from an aqueous solution, or crystallize anhydrous 2′-FL polymorph I from a dried 2′-FL syrup where the 2′-FL, in both cases, was produced by a hydrogenation reaction.
However, because of the byproducts produced in the aqueous culture medium during fermentation of 2′-FL, there has been a continuing need for an efficient process for crystallizing 2′-FL from the aqueous culture medium.